"I bet someone hasn't come in here and screamed in 30 years," he said early Monday morning after capturing his second Daytona 500 victory. "But they used to!"

Few in the 55-year history of NASCAR's most fabled racetrack would have had as many reasons to be elated as Earnhardt was after weathering the longest day in Daytona history.

--He broke a 55-race winless drought in the Sprint Cup Series (he missed two races because of concussions) and began the 2014 season emphatically after a winless 2013 in which he finished second five times.

--He won the Great American Race for the second time (10 years after his first triumph) -- one more than his father, whose iconic No. 3 returned to the track (with rookie Austin Dillon) for the first time since the seven-time champion was killed on the last lap of the 2001 Daytona 500.

--He virtually assured himself a berth in the Chase for the Sprint Cup with his 20th victory on the Cup circuit but only his second in almost six years, answering the question of whether an emphasis on winning might hurt his title chances and whether the impending departure of crew chief Steve Letarte (who will leave for an NBC analyst role in 2015) would cause distractions.

"We're going for the jugular this year," said Earnhardt, who led the final 18 laps in a race that ended under caution at 11:18 p.m., nearly 11 hours after it began because of a rain delay of more than six hours.

Under NASCAR's new Chase for the Sprint Cup format, any race winner qualifies for the season-ending 10-race playoff, which also will feature elimination rounds and a winner-take-all season finale among four drivers.

"It's big for a lot of reasons," said Denny Hamlin, who finished second Sunday and one spot short of becoming the first driver to sweep the Cup races of Speedweeks. "He's obviously going into the last year with (Letarte). They going to start making Chase plans now. They're very flexible in what they can try.

"As far as the race win, it's obviously very significant that any Earnhardt wins at Daytona."

WATCH: Dale Earnhardt Jr. celebrates in victory lane

Earnhardt fended off a challenge by Brad Keselowski (third) on the final restart and got drafting help from Hendrick Motorsports teammate Jeff Gordon (fourth) to protect the lead.

"He's such a competitor, and there's no better race to win than the Daytona 500. Especially for Junior," said Gordon, Earnhardt's Hendrick Motorsports teammate. "There is something unique and special because of his fan base."

Though he hadn't won at Daytona since 2004, he'd finished runner-up in three of the past four years at the season opener.

"Winning this race is the greatest feeling that you can feel in this sport, aside from accepting trophy for the championship," said Earnhardt, who led a race-high 54 laps. "I didn't know if I'd ever get a chance to feel that again.

"This is amazing. I can't believe this is happening. I'll never take this for granted, man. This doesn't happen twice, let alone once. Just real thankful."

Keselowski, whose big break in NASCAR came when he was hired by Earnhardt for a Nationwide ride seven years ago, said, "I'm happy for my friend.

"He did a great job. He's been right there. He runs restrictor plates as an elite driver; he's probably in the top three. He hasn't gotten the win he deserved a couple of times from a whole bunch of circumstances out of his control. He was due."

There still were plenty of anxious moments in the final 60 laps, which featured four multicar crashes of at least six cars.

"Everybody kept telling me over the radio, 'There's more rain coming,' (and) I think that really added to the anxiety and rush of pace even more so than the break," Keselowski said. "I think everyone raced a hard 500-mile race. That has to be the hardest 500 race ever, probably one of the best.

"You could run the bottom, the top, the middle. At one point in the race, handling started to come into play and skill level really showed up from a driver's perspective. I couldn't be more pleased as both a participant and naturally a fan of the sport with how the 500 went."

Gordon, who was making his 726th start in NASCAR's premier series in a career that dates back to 1992, was blown away by the long, drama-filled day.

"I don't know what happened," said Gordon, a three-time Daytona 500 winner. "The sun went down and the rain went away and the track dried and everyone switched their brains to 'this is a 10-lap shootout.' It was unbelievable. I've never seen at Daytona 500 like that."

Danica Patrick, driver of the #10 GoDaddy Chevrolet, and Paul Menard, driver of the #27 Peak/Menard's Chevrolet, are involved in an incident during the NASCAR Sprint Cup Series Daytona 500 at Daytona International Speedway on February 23, 2014 in Daytona Beach, Florida. (Photo: Jared C. Tilton, Getty Images)

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The race was relatively clean until a 13-car wreck on lap 145 that started when Kevin Harvick and Brian Scott made contact, triggering a chain reaction off turn 4. The driver who took the heaviest impact was Danica Patrick, whose No. 10 Chevrolet turned hard into a section of the wall uncovered by a SAFER barrier.

Patrick, who led the Daytona 500 for the second consecutive year (pacing laps 85-86), was unhurt in the incident but was disappointed in the outcome.

"I'm just upset the GoDaddy car felt really good and was the best we had in Speedweeks," she said. "I felt everything was going pretty well. It's just upsetting, a culmination of sitting around all day. It's a bummer, but that's the excitement of speedway racing that anything can happen. It's unfortunate I was on the short end of the accident, but that's the type of thing that happens."

Said Michael Waltrip: "The cars are grippy. People are crazy. They like to go. There are a lot of lanes, and people are trying to use every one of them. It's a great race for the fans."

Aric Almirola, also involved in the wreck, said the intensity increased as the race progressed with the threat of rain lurking that could shorten the race early.

"It's been a lot more chaotic for sure," he said. "The track has a lot more grip, so people are taking a lot more risks. The cars drive a lot better at night."

After a break of more than six hours, the racing was furious as soon as the green flag flew at 8:52 p.m. Cars began scrambling for position immediately, forming in several three-wide rows. Joe Gibbs Racing teammates Hamlin and Kyle Busch quickly took command, leading 11 of 13 laps after the restart, but both Toyota drivers ran into trouble.

Hamlin had problems with his radio, and Busch got penalized with a pass-through penalty for leaving his pit stall with an air gun attached. Coupled with an earlier pit miscue, it was another tough break for JGR, which hasn't won the Daytona 500 in 21 years.

Tony Stewart's bid for a storybook ending to his comeback story ended in another Daytona 500 disappointment. Stewart, who was returning after a six-month layoff because of a broken right leg, began experiencing engine and fuel pressure problems shortly after the race's midpoint.

The problems necessitated several pit stops under green for the three-time champion, who now is 0 for 16 in NASCAR's crown jewel despite 19 wins at Daytona International Speedway.

Severe weather and red flag

The first 38 laps before the delay were relatively uneventful as drivers seemed content to log laps in order.

Pole-sitter Austin Dillon, in the first start of the No. 3 Chevrolet since Earnhardt Sr.'s death here, led the first lap before yielding first to Hamlin, who was trying to become the first Sprint Cup driver to sweep the Sprint Unlimited, Budweiser Duel qualifying race and Daytona 500.

By the eighth lap, the 43 cars were strung out in a long single-file line around the 2.5-mile oval. The action also was limited by poor handling for many drivers. Starting in muggy 75-degree weather after running the Unlimited and qualifying races in cooler conditions at night, cars didn't respond as well as earlier in Speedweeks when many had hailed a taller spoiler with enhanced passing by increasing the closing rate and reinvigorating side-drafting.

Kyle Larson, one of seven rookies starting the Great American Race, suffered a tire problem on the third lap, and his No. 42 Chevrolet caused the first yellow flag with a Turn 2 spin on lap 23.

During the first round of pit stops, two-time Daytona 500 champion Matt Kenseth pulled into his stall backward after missing his signboard and colliding with Trevor Bayne.

That was about it for memorable moments until the yellow flag flew on lap 33 for fluid put down by an engine failure in Martin Truex Jr.'s car. Truex, in his first season with Furniture Row Racing, was the race's second-place qualifier but had to start in the back of the field after wrecking in a qualifying race Thursday night. He finished 43rd.

The rain began during the caution period shortly after 2 p.m., and NASCAR stopped the cars after six laps at 2:13.

That began a red flag that lasted six hours, 21 minutes and 40 seconds and brought intermittent storms, a tornado warning and a tidal wave of confusion for many watching the delay on TV.

Fox showed a replay of last year's race, which was won by Johnson, but many viewers and some media outlets apparently thought they were watching a live broadcast. As the congratulations began pouring in via texts and social media after the replay ended around 5:45 p.m., the six-time champion poked fun on Twitter: "I hear I won the #Daytona500? Haha! I also have friends confused and texting congratulations to me. #2013Replay."

"The coolest thing about this weather is we were able to run two Daytona 500s in one day," Clint Bowyer said in a Fox interview during the delay. "Jimmie won the first one apparently. I'm going to win the next one."

Sunday's long delay was the latest in a series of bizarre twists in NASCAR's signature event.

Two years ago, the 54th edition of the race was postponed for the first time in its history. After starting Monday night, it was delayed by two hours after track cleanup from a Turn 3 fireball because Juan Pablo Montoya collided with a jet dryer.

In 2010, the race was delayed twice for more than two hours because of a pothole. Rain also shortened the race in 2009.

Lee Petty (42), driving an Oldsmobile, and Johnny Beauchamp (73), driving a Thunderbird, were neck and neck on the last lap of the inaugural Daytona 500 in 1959, but Petty nosed out Beauchamp at the finish line. (Photo: AP)

Former Miss USA Diana Batts, of Washington, D.C., gives a big kiss to Mario Andretti after he won the 1967 Daytona 500. Andretti remains the only driver ever to win the Indianapolis 500 (1969), Daytona 500 (1967) and the Formula One World Championship (1978). (Photo: AP)

A.J. Foyt gets a big kiss from Union 76 Racestopper Cheryl Johnson after winning the 1972 Daytona 500. Foyt is the only driver to win the Indianapolis 500 (which he won four times), the Daytona 500, the 24 Hours of Daytona, and the 24 Hours of Le Mans. (Photo: AP)

Cale Yarborough, right, kicks and pushes Bobby Allison, center, who is catching his leg as Donnie Allison, left, tries to pull his brother free from the fight which started after Yarborough collided with Donnie on the last lap of the 1979 Daytona 500. (Photo: Ric Feld, AP)

Richard Petty, (middle, with STP cap and sunglasses), poses with his family after winning his sixth Daytona 500 title in 1979. Petty won for the seventh and final time in 1981. (Photo: Daytona Racing Archives)

Bobby Allison, right, celebrates his victory in the 1988 Daytona 500 by pouring a Miller beer over the head of his son Davey Allison, who he beat in an emotional finish. Davey Allison won the 1992 race, while Bobby Allison also won in 1982 and 1978. (Photo: Dozier Mobley, Getty Images)

Darrell Waltrip celebrates his lone Daytona 500 title by performing the "Ickey Shuffle," a dance created by NFL player Ickey Woods, after winning the 1989 Great American Race. (Photo: RacingOne ISC Archives via Getty Images)

Crew members line up along pit road to congratulate Dale Earnhardt as the NASCAR legend finally wins his first Daytona 500 in 1998, 20 years after his first Daytona 500 start in 1979. (Photo: Roger Simms, Daytona Beach News-Journal via AP)

Dale Earnhardt (3) hits the wall after getting hit by Ken Schrader (36) during the 2001 Daytona 500. Earnhardt died as a result of the crash that stands as one of the most horrific moments in NASCAR history. (Photo: Bob Sweeten, AP)

Shortly after winning the 2001 Daytona 500, Michael Waltrip talks about the death of friend and competitor Dale Earnhardt, who died after crashing on the last lap. Waltrip would have a chance to better celebrate after winning the 2003 Daytona 500. (Photo: Terry Renna, AP)

Two-time Daytona 500 champion Sterling Marlin gets a reprimand from a track official after he tried to pull a bent piece of sheet metal away from his tire during a red-flag stop in the 2002 race. Marlin's gaffe will forever be part of NASCAR's lore, with some saying his illegal attempt to fix his car under the red flag cost him a victory. (Photo: Dow Graham, AP)

Crew members converge on Dale Earnhardt Jr., left, at the start-finish line after he won the 2004 Daytona 500, three years after his father died as a result of a last-lap crash in the 2001 event. (Photo: Jonathan Ferrey, Getty Images)

Workers repair damage to the track as a result of a pothole in Turn 2 on lap 122 during the 2010 Daytona 500. The race was red-flagged for almost two hours before Jamie McMurray eventually won. (Photo: Jerry Markland, Getty Images for NASCAR)

Safety crews work to put out a fire from a jet-fueled track dryer that was hit by Juan Pablo Montoya's car (not pictured) under caution during the 2012 Daytona 500. (Photo: Andrew Weber, USA TODAY Sports)

Safety workers clean up the track with Tide laundry detergent after a jet-fueled track dryer burst into flames when it was struck by Juan Pablo Montoya's car under caution during the 2012 Daytona 500. (Photo: John Harrelson, Getty Images for NASCAR)